OBJECTIVES: (1) To establish on an enzymatic level a catabolic pathway for subterminal oxidation of aliphatic hydrocarbons by microorganisms, i.e. alkane yields secondary alcohol yields methyl ketone yields acetate ester yields primary alcohol plus acetate, (2) To determine if this pathway is operative in insects, specifically the ant, for the biosynthesis of some of their pheromones (methyl ketones, acetate esters), and to ascertain if this process is mediated by symbiotic micoorganisms. METHODS: (1) Standard methods of enzyme purification, (2) Demonstrating conversions of C14-labeled intermediates in a precursor/product relationship in the ant by radio-chemical assays, (3) Isolation of organisms from ants by standard microbiological methods and assaying their ability to transform these compounds. Intermediates produced in this pathway by microorganisms are the same or similar to compounds that have wide-ranging effects on various $ biological systems in low concentrations. The role of microorganisms in the degradation of oil pollutants to these compounds in the environment may be of ecological importance.